Discusses merits of using sigma-pi model of ethylene as a teaching aid in introductory organic chemistry. The nonmathematical treatment of sigma-pi bonding is then extended to such phenomena as conjugation, hyperconjugation, Markovnikoff addition, aromaticity, and aromatic substitution. (SK)

Discusses the problem of symmetry avoidance using water as an historical example. Uses simple pi systems for the analysis. Provides methodology and examples. Investigates two naive arguments. (MVL)

Discussed is single crystal X-ray crystal structure analysis. A common link between the NMR imaging and the traditional X-ray crystal structure analysis is reported. Claims that comparisons aid in the understanding of both techniques. (MVL)

Discusses three broad classes of magnetic behavior: diamagnetic, paramagnetic, and ferromagnetic. Presents a simple lecture demonstration using an overhead projector to synthesize triiron tetraoxide and to show its interaction with a magnetic field and comparing it to a paramagnetic material. (MVL)

Finds that a logical application of the simple rules of the molecular orbital bonding theory for diatomic molecules predicted the existence of three spin isomers of the oxygen molecule: one triplet form with two unpaired electrons and two singlet forms with all electrons paired. (MVL)

Discusses a new method for determining the eigenvalues of the Schroedinger equation when the potential energy function does not have a simple form. Describes the mathematical methods and provides an application. Lists limitations to the method. (MVL)

Questions the use of the Reactivity Selectivity Principle (RSP) by teachers and authors of texts in discussing organic reaction mechanisms. Provides some applications and failures of the use of the RSP, reviews some quantitative aspects of the RSP, and discusses some of the rationalization of the RSP failures. (TW)

Addresses the requirements of high school students and noncrystallographers in lectures on crystals, diffraction, and structure analysis. Discusses basic understanding and a sequence that addresses these requirements. Suggests visual and descriptive teaching methods used in this effort. (CW)

Uses simple pulse NMR experiments to discuss Fourier transforms. Studies the generation of spin echoes used in the imaging procedure. Shows that pulse NMR experiments give signals that are additions of sinusoids of differing amplitudes, frequencies, and phases. (MVL)

Describes a procedure for constructing point groups based on the symmetric parent molecules of methane and adamantane. Intended for use in teaching concepts such as subgroups and cosets to beginners in group theory. (TW)

Uses the electron cloud and Lewis structure models to present resonance. Shows resonance bonding as an increase in dot density of the electron cloud. Provides classroom presentation ideas. (MVL)

Reviews the basis for the technique and its experimental requirements. Describes a few examples of the analytical problems to which surface-enhanced Raman spectroscopy (SERS) has been and can be applied. Provides a perspective on the current limitations and frontiers in developing SERS as an analytical technique. (MVL)

Presents the mechanistic ideas underlying reactions between nucleophiles and carbonyl compounds as well as some popular misconceptions. Relates reactions of carboxylic acid derivatives to those of aldehydes and ketones. Discusses leaving group ability and the ability of carbonyl oxygen to accept a negative charge. (Author/MVL)

Treats the development of general stereochemical principles in historical fashion. Discusses work by Pasteur, van't Hoff, and Le Bel. Considers sugars by configuration, anomeric forms, ring forms, and conformational isomers. Presents numerous diagrams and thorough explanations. (MVL)

Presents an exercise to get students more intimately involved in the three dimensional nature of basic units by constructing models. Uses balsa wood, glue, sandpaper, and a square. Studies seven crystals: cubic, hexagonal, monoclinic, orthorhombic, rhombohedral, tetragonal, and triclinic. Plans are available for a Macintosh computer. (MVL)